ICD-10 · PDGM grouping
A84 Tick-borne viral encephalitis
All 5 codes in the A84 family, with the PDGM clinical group, comorbidity subgroup and primary-position rule CMS assigns, read from the CMS grouper crosswalk v07.2.26 and the CDC FY2027 code file.
Codes in family
5
Can lead a claim
5
Cannot lead a claim
0
What CMS assigns to A84
All 5 codes group to Neuro Rehabilitation. None of the 5 is assigned a comorbidity subgroup. Every code can lead a claim. CMS attaches a code-first note to 1 of the 5.
Code first
CMS grouper convention 2, on A84.89. Code first:
- , if applicable, transfusion related infection (T80.22-)
Every code in A84
Descriptions are CDC’s FY2027 wording; where CMS’s grouper abbreviates one, its form is shown beneath.
| Code | Description | Primary position | Clinical group | Comorbidity subgroup |
|---|---|---|---|---|
| A84.0 | Far Eastern tick-borne encephalitis [Russian spring-summer encephalitis]CMS: Far Eastern tick-borne encephalitis | Can lead a claim | B | None |
| A84.1 | Central European tick-borne encephalitis | Can lead a claim | B | None |
| A84.8 Other tick-borne viral encephalitis | ||||
| A84.81 | Powassan virus disease | Can lead a claim | B | None |
| A84.89 | Other tick-borne viral encephalitis | Can lead a claim, code first applies | B | None |
| A84.9 | Tick-borne viral encephalitis, unspecified | Can lead a claim | B | None |
Sources: CMS HH PPS Grouper Software v07.2.26, effective 2026-10-01, for the clinical group, comorbidity subgroup, code-first conventions and primary-position flags; CDC NCHS ICD-10-CM FY2027 code descriptions for the family title and code wording. This is the crosswalk Medicare runs a claim through. Grouping also depends on admission source, timing, the OASIS functional items and the rest of the diagnosis list.
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